1. Field of the Disclosure
This disclosure generally relates to exploration and production of hydrocarbons involving investigations of regions of an earth formation penetrated by a borehole. More specifically, the disclosure relates to the characterizing the earth formation using a logging tool in the borehole.
2. Description of the Related Art
A variety of techniques are currently utilized in characterizing earth formations. These methods are designed to determine formation parameters, including, among other things, the resistivity, porosity, dielectric susceptibility, and permeability of a rock formation surrounding a borehole drilled for recovering the hydrocarbons. Electroacoustic methods for earth borehole logging are well known to persons having an ordinary level of skill in the art, and various devices and various techniques have been described for this purpose. Typically, the tools designed to provide the desired information are used to log the borehole. Much of the logging is done after the boreholes have been drilled.
Extensive work has been done in the determination of formation properties using electroacoustic methods. In an electroacoustic method, an electric field may be applied at a 90 degree angle to an interface between a porous earth formation and a borehole fluid. An alternative magnetic field may then be applied to the surface of the earth formation.